Plasma-based etching can be an important processing step in the fabrication of semiconductor devices and integrated circuits. However, the plasma-based etching can result in contaminants, including oxides and damaged or amorphous silicon. The presence of oxides and damaged silicon on the surfaces of materials, including semiconductor substrates containing silicon and metals, can adversely affect subsequent fabrication processes, thereby affecting the performance of the semiconductor device. In particular, when oxides and other contaminants are formed on silicon, the oxides or other contaminants can be electrically insulating and can be detrimental to electrical pathways of contacts in the semiconductor device or integrated circuit.
Memory devices, such as 3-dimensional vertical NAND (V-NAND) memory devices, may include vertical structures having alternating layers of oxide and nitride (ONON) on a silicon substrate. In some implementations, devices may have alternating layers of oxide and polysilicon (OPOP). High-aspect ratio openings may be formed between each of the vertical structures. The high-aspect ratio openings may subsequently serve as electrical contacts in the memory device. As used herein, high-aspect ratio openings may also be referred to as high-aspect ratio contacts. In some implementations, the high-aspect ratio openings can take the shape of a hole, slit, or a trench. The high-aspect ratio openings may be formed using a plasma-based etch. The plasma-based etch may use a significant concentration of oxygen and high ionization energies, which can result in the formation of oxides (e.g., silicon oxide), damaged silicon, and other contaminants (e.g., carbon) at the bottom of the high-aspect ratio openings. The openings may be filled or substantially filled with metal to create an electrical contact in the memory device. However, upon forming electrical contacts in the high-aspect ratio openings, the presence of the undesired oxides, damaged silicon, and other contaminants can be detrimental to the performance of the memory device.